Internal voltage generator

ABSTRACT

An internal voltage generator maintains stable level of an internal voltage without increasing physical area. The internal voltage generator includes an active level detector for detecting a level of an internal voltage by comparing the level of the internal voltage and a level of a reference voltage to thereby output a first active driving signal, a first active driver for providing the internal voltage in response to the first active driving signal, a driving time controller for generating a time driving signal activated for a predetermined time, an active driving controller for activating a second active driving signal while the time driving signal is activated and for outputting the first active driving signal as the second active driving signal while the time driving signal is inactivated, and a second active driver for providing the internal voltage in response to the second active driving signal.

FIELD OF INVENTION

The present invention relates to a semiconductor design technique; and, more particularly, to an internal voltage generator for maintaining stable level of an internal voltage.

DESCRIPTION OF PRIOR ART

As a semiconductor memory device is used for a mobile product which requires low power consumption, current consumption of the semiconductor becomes an important factor in evaluating device performance.

Hence, the semiconductor memory device uses a stand-by driver which has low driving capability in stand-by mode of low current consumption, during which an external command is waited without actual operation, while it supplies current for additionally driving an active driver in active mode during which more current is required for performing operations from input of the external command.

In other words, the semiconductor memory device uses a stand-by driver of low driving power because response time need not be fast in the stand-by mode of low current consumption, while it additionally uses the active driver of high driving power because the response time should be fast in the active mode of high current consumption.

FIG. 1 shows an internal circuit diagram of a conventional internal voltage generator in prior art.

Referring to FIG. 1, the conventional internal voltage generator includes a normal level detecting unit 10 for detecting level of an internal voltage VCORE relative to a reference voltage VR, a normal driver PM1 for providing the internal voltage VCORE under the control of the normal level detecting unit 10, an active period detecting unit 20 for outputting an active period signal ratv when active period is detected, an active level detecting unit 30 for detecting the level of the internal voltage VCORE relative to the reference voltage VR in response to the active period signal ratv, a first active driver PM2 for providing the internal voltage VCORE under the control of the active level detecting unit 30, a driving time controlling unit 40 for generating a second active driving signal act_tm_drv that is activated for a predetermined time after activation of the active period signal ratv, and a second active driver PM3 for providing the internal voltage VCORE during the activation period of the second active driving signal act_tm_drv.

The active period detecting unit 20 activates the active period signal ratv in response to an active command ACT and deactivates the active period signal ratv in response to a pre-charge signal PCG.

Here, the reference voltage is a desired level for the internal voltage VCORE.

FIG. 2 is a waveform diagram for an internal voltage generator in FIG. 1, which will be referred to describe the operation of the conventional voltage generator in prior art.

Basically, the normal level detecting unit 10 is maintained continuously as turned on to detect the level of the internal voltage VCORE in order to drive the normal driver PM1. That is, the normal level detecting unit 10 activates a normal driving signal nrm_drv when the internal voltage VCORE falls down to a lower level than the reference voltage VR in order to make the normal driver PM1 supply the internal voltage VCORE, and deactivates the normal driving signal nrm_drv when the internal voltage VCORE rises up to a higher level than the reference voltage VR to turn off the normal driver PM1.

On the other hand, when the active command ACT and an row address are inputted, thousands of memory cell data that are connected to the corresponding word-lines are sensed and amplified and, accordingly, consumption of the internal voltage VCORE is increased and, in turn, the level of the internal voltage VCORE falls down fast.

At this time, the active period detecting unit 20 activates the active period signal ratv in response to input of the active command ACT. Accordingly, the active level detecting unit 30 detects the level of the internal voltage VCORE relative to the reference voltage VR in response to the active period signal ratv to make the first active driver PM2 additionally supply the internal voltage VCORE. Further, the driving time controlling unit 40 activates the second active driving signal act_tm_drv having a predetermined activation period from the activation of the active period signal ratv in order to drive the second active driver PM3 to supply the internal voltage VCORE.

Since the first active driver PM2 and the second active driver PM3 additionally supply the internal voltage VCORE, the level of the internal voltage VCORE is increased to be maintained as the level of the reference voltage VR.

Then, during the activation period of the active period signal ratv, the normal and active level detecting units 10, 20 keep detecting the level of the internal voltage VCORE to drive the normal driver PM1 and the first active driver PM2 so as to maintain the internal voltage VCORE as the reference voltage VR.

Then, when the pre-charge command PCG is inputted, the active period detecting unit 20 deactivates the active period signal ratv so as to turn off the active level detecting unit 30. Accordingly, during deactivation period of the active period signal ratv, only the normal level detecting unit 10 is active to detect the level of the internal voltage VCORE so that the normal driver PM1 can be driven to maintain stable level of the internal voltage VCORE.

As described above, the conventional internal voltage generator maintains stable level of the internal voltage VCORE with the normal level detecting unit 10 that is continuously driven and the normal driver PM1 that is under the control of the normal level detecting unit 10, and maintains stale level of the internal voltage VCORE with the first and the second active driving units PM2, PM3 when consumption of the internal voltage VCORE is increased from the active command ACT.

Particularly, since the highest current consumption occurs at the initial input timing of the active command ACT among the active period, the driving time controlling unit 40 for controlling driving time as a predetermined time α when the active command ACT is inputted and the second active driver PM3 under the control of the driving time controlling unit 40 are used for supplying the internal voltage VCORE in addition to the active level detecting unit 30 and the first active driver PM2 that are driven with level detecting of the voltage.

As described above, in the conventional internal voltage generator, the number of the drivers within its region is changed depending on the consumption of the internal voltage so that unnecessary size increase of the driver and unnecessary current consumption can be avoided.

On the other hand, the internal voltage is supplied through the normal driver and the first active driver after the initial time of the active period. If the consumed amount of the internal voltage is higher than the supplied amount, the internal voltage becomes unstable.

Such an unstable voltage after the initial time of the active period can be avoided with larger size of the first active driver. However, such a solution increases unnecessary area.

SUMMARY OF INVENTION

It is, therefore, an object of the present invention to provide an internal voltage generator for maintaining stable level of an internal voltage without increasing physical area.

In accordance with an aspect of the present invention, there is provided an internal voltage generator including a normal level detecting unit for detecting level of the internal voltage relative to a reference voltage; a normal driver for supplying the internal voltage under the control of the normal level detecting unit; an active period detecting unit for detecting an active period to output an active period signal; an active level detecting unit for detecting the level of the internal voltage relative to the reference voltage in response to the active period signal; a first active driver for supplying the internal voltage under the control of the active level detecting unit; an active driving controlling unit for activating a first active driving signal for a predetermined initial time of the active period in response to the active period signal and the output signal of the first active level detecting unit and for activating the first active driving signal depending on the internal voltage relative to the reference voltage after the predetermined initial time of the active period; and a second active driver for supplying the internal voltage in response to the first active driving signal.

In accordance with another aspect of the present invention, there is provided an internal voltage generator including a normal driver for supplying an internal voltage; a first and a second drivers for supplying the internal voltage; a normal level detecting unit for detecting the internal voltage relative to a reference voltage to control driving of the normal driver; an active period detecting unit for detecting an active period to output an active period signal; an active level detecting unit for detecting the level of the internal voltage relative to the reference voltage in response to the active period signal to control driving of the first active driver; a test mode signal generating unit for generating a test mode signal; and an active driving controlling unit for driving the second active driver without regard to the level of the internal voltage for a predetermined time after activation of the active period signal and for driving the second active driver in response to the test mode signal and the output signal of the active level detecting unit after the predetermined time.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a conventional internal circuit diagram of an internal voltage generator;

FIG. 2 is a waveform diagram for an internal voltage generator in FIG. 1;

FIG. 3 provides an internal circuit diagram of an internal voltage generator in accordance with the first embodiment of the present invention;

FIG. 4 is a waveform diagram for an internal voltage generator in FIG. 3;

FIG. 5 offers an internal circuit diagram of an internal voltage generator in accordance with the second embodiment of the present invention; and

FIG. 6 is an internal circuit diagram of an internal voltage generator in accordance with the third embodiment of the present invention.

DETAILED DESCRIPTION OF INVENTION

Hereinafter, a digital temperature sensor and a self-refresh driving device using the same in accordance with the present invention will be described in detail referring to the accompanying drawings.

FIG. 3 provides an internal circuit diagram of an internal voltage generator in accordance with the first embodiment of the present invention.

Referring to FIG. 3, the internal voltage generator according to the first embodiment of the present invention includes a normal level detecting unit 100 for detecting level of an internal voltage VCORE relative to a reference voltage VR, a normal driver PM4 for supplying the internal voltage VCORE under the control of the normal level detecting unit 100, an active period detecting unit 200 for detecting active period to output an active period signal ratv, an active level detecting unit 300 for detecting the level of the internal voltage VCORE relative to the reference voltage VR in response to the active period signal ratv, a first active driver PM5 for supplying the internal voltage VCORE under the control of the active level detecting unit 300, active driving controlling units 400, 500 for activating a second active driving signal ovd_onb for a predetermined initial time of the active period in response to the active period signal ratv and the output signal act_lv_drv from the active level detecting unit 300 and for activating the second active driving signal ovd_onb depending on the level of the internal voltage VCORE relative to the reference voltage VR after the predetermined initial time of the active period, and a third active driver PM6 for supplying the internal voltage VCORE in response to the second active driving signal ovd_onb.

Further, the active driving controlling units 400, 500 include a driving time controlling unit 400 for generating a time driving signal tm_drv that is activated for a predetermined time after activation of the active period signal ratv, and an additional controlling unit 500 for activating the second active driving signal ovd_onb during activation of the time driving signal tm_drv and for outputting the output of the active level detecting unit 300 as the second active driving signal ovd_onb during deactivation of the time driving signal tm_drv.

The additional controlling unit 500 includes a buffer having serially coupled inverters I1, I2 for buffering the output signal act_lv_drv from the active level detecting unit 300, a NAND gate ND1 for receiving the output signal from the buffer and the time driving signal tm_drv, and an inverter I3 for inverting the output signal of the NAND gate ND1 to output the second active driving signal ovd_onb.

FIG. 4 is a waveform diagram for an internal voltage generator in FIG. 3, which will be referred to describe the operation of the internal voltage generator according to the first embodiment of the present invention.

First, when an active command is applied, the internal voltage VCORE is consumed due to operation of corresponding loading element 600 such that the level of the internal voltage VCORE falls down.

At this moment, the active period detecting unit 200 activates the active period signal ratv in response to the active command ACT so as to additionally drive the first and the second active drivers PM5, PM6 for supplying the internal voltage VCORE.

That is, the active level detecting unit 300 detects the level of the internal voltage VCORE relative to the reference voltage VR in response to the active period signal ratv to generate the first active period driving signal act_lv_drv to have the first active driver PM5 supply the internal voltage VCORE.

Further, the active driving controlling units 400, 500 output the time controlling signal tm_drv, that is activated by the driving time controlling unit 400 during the initial time of the active period, as the active driving signal ovd_onb through the additional controlling unit 500 to have the second active driver PM6 supply the initial voltage VCORE. In turn, when the time driving signal tm_drv is deactivated, the additional controlling unit 500 outputs the output signal act_lv_drv of the active level detecting unit 300 as the second active driving signal ovd_onb to have the second active driver PM6 supply the internal voltage VCORE.

As such, the internal voltage generator according to the first embodiment of the present invention have the second active driver PM6 supply the internal voltage VCORE under the control of the active level detecting unit 300, that is conventionally driven during the predetermined initial time α without regard to the level of the internal voltage VCORE, further after the predetermined initial time α of the active period.

Accordingly, since the internal voltage VCORE is supplied through the first and the second drivers PM5, PM6 during the active period, driving power of the drivers for supplying the internal voltage VCORE during the active period is increased without increasing area so that the level of the internal voltage VCORE can be maintained stable.

On the other hand, since the active level detecting unit 300 needs a response time from detection of the level of the internal voltage VCORE relative to the reference voltage VR to turning on/off the first and the second active drivers PM5, PM6, the first and the second active drivers PM5, PM6 cannot be turned off immediately when the internal voltage becomes higher than the reference voltage, which makes the internal voltage rises higher than the reference voltage.

Further, since the internal voltage VCORE is supplied through the first and the second active drivers PM5, PM6, the level of the internal voltage VCORE excessively increases.

Accordingly, another internal voltage generator for monitoring the level increase of the internal voltage VCORE due to additional driving of the second active driver PM6 with test mode will be described with referring to FIG. 5.

FIG. 5 offers an internal circuit diagram of an internal voltage generator in accordance with the second embodiment of the present invention.

Referring to FIG. 5, an additional controlling unit 800 of the internal circuit diagram of an internal voltage generator according to the second embodiment of the present invention includes a buffer, having two inverters I4, I5 serially coupled to each other, for buffering the output signal from the active level detecting unit 300, a NOR gate NR1 receiving the output signal of the buffer and the test mode signal tm, an inverter I6 for inverting the output signal of the NOR gate NR1, a NAND gate ND2 receiving the output signal of the inverter I6 and the time driving signal tm_drv, and an inverter I7 for inverting the output signal of the NAND gate ND2 to output the second active driving signal ovd_onb.

On the other hand, compared to the internal voltage generator of the first embodiment, the internal voltage generator of the second embodiment further includes a test mode signal generating unit 700.

Accordingly, since the internal voltage generator of the second embodiment is similar to the example of the first embodiment (FIG. 3) except for the additional controlling unit 800 and the test ode signal generating unit 700, it will be omitted for the detailed description.

In the following, it will be described for the operation of the active driving controlling units 400, 500 with the test mode signal generating unit 700.

When the active period detecting unit 200 activates the active period signal ratv in response to input of the active command ACT, the driving time controlling unit 400 outputs the time driving signal tm_drv that is activated for a predetermined time after activation of the active period signal ratv.

First, in activation of the time driving signal tm_drv, the additional controlling unit 800 outputs the time driving signal tm_drv as the second active driving signal ovd_onb, thereby the second active driver PM6 supplies the internal voltage VCORE for a predetermined time without regard to the level of the internal voltage VCORE.

Further, in deactivation of the time driving signal tm_drv, the additional controlling unit 800 deactivates the second active driving signal ovd_onb to logic level ‘L’ without regard to the output signal act_lv_drv of the active level detecting unit 300 if the output signal tm of the test mode signal generating unit 700 is activated to logic level ‘H’. Accordingly, the second active driver PM6 is turned off by the second active driving signal ovd_onb.

The additional controlling unit 800 outputs the output signal act_lv_drv of the active level detecting unit 300 as the second active driving signal ovd_onb when the output signal tm_of the test mode signal generating unit 700 is deactivated in deactivation period of the time driving signal tm_drv, thereby the second active driver PM6 is driven by the active level detecting unit 300.

As described above, the internal voltage generating unit of the second embodiment further includes the test mode signal generating 700 so that the second active driver PM6 can be controlled by the active level detecting unit 300 or turned off by the test mode signal tm when the time driving signal tm_drv is deactivated during the active period.

Therefore, the internal voltage generator of the second embodiment is capable of monitoring if additional driving of the second active driver PM6 is needed with the test mode signal tm in deactivation period of the time driving signal tm_drv during the active period or not, thereby excessive increase of the internal voltage VCORE can be avoided.

On the other hand, compared to the internal voltage generators of the first and the second embodiments that share the active level detecting unit 300 for driving control of the first active driver PM5 to control driving of the second active driver PM6, another internal voltage generator for avoiding excessive increase of the internal voltage will be described with reference to FIG. 6.

FIG. 6 is an internal circuit diagram of an internal voltage generator in accordance with the third embodiment of the present invention, which further includes a second active level detecting unit 900 for driving only the second active driver PM6, compared to the second embodiment (FIG. 5).

On the other hand, the normal level detecting unit 100 and the first active level detecting unit 300 detect the level of the internal voltage VCORE relative to the first reference voltage VR1 While the second active level detecting unit 900 detects the level of the internal voltage VCORE relative to the second reference voltage VR2.

Particularly, since the level of the second reference voltage VR2 is lower than the first reference voltage VR1, the second active level detecting unit 900 activates its output signal only if the level of the internal voltage VCORE is lower than the second reference voltage VR2 to drive the second active driver PM6.

Accordingly, during the initial time of the active period, the internal voltage generator of the third embodiment supplies the internal voltage VCORE through the first active driver PM5 that is driven through the first active level detecting unit 300 and the second active driver PM6 that is driven for a predetermined time. After the initial time of the active period, the internal voltage VCORE is supplied through the normal driver PM4 and the first active driver PM5 when the level of the internal voltage VCORE is lower than the first reference voltage VR1, while the internal voltage VCORE is supplied through the first and the second active drivers PM5, PM6 when the level of the internal voltage VCORE is lower than the second reference voltage VR2.

Therefore, after the initial active period, the first and the second active drivers PM5, PM6 supply the internal voltage VCORE so that excessive level increase of the internal voltage can be avoided.

Further, because the internal voltage generator of the third embodiment of the present invention includes the test mode signal generating unit 700, it can be monitored with the test mode signal if the internal voltage VCORE is increased excessively due to driving of the second active driver PM6 or not.

As described above, the internal voltage generators of the first to the third embodiments of the present invention drive the active driver, that is conventionally driven only for the predetermined initial time of the active period, depending on the level of the internal voltage after the initial time, thereby the internal voltage is supplied stably without increasing physical area for increasing driving power of the driver.

Further, the internal voltage generators of the second and the third embodiments are capable of monitoring excessive increase of the internal voltage due to the active driver, that is additionally driven after the predetermined initial time, through the test mode signal, thereby excessive increase of the internal voltage can be avoided.

Further, the internal voltage generator of the third embodiment includes the separate level detecting unit for the active driver that is driven after the predetermined initial time of the active period to adjust the level of the reference voltage, thereby additional driving point of the active driver can be adjusted to avoid excessive increase of the internal voltage.

On the other hand, as described above, the separate second active level detecting unit for the second active driver can be applied in the internal voltage generator of the first embodiment, thereby excessive increase of the internal voltage can be avoided.

The present application contains subject matter related to Korean patent application No. 2004-89330, filed in the Korean Patent Office on Nov. 4, 2004, the entire contents of which being incorporated herein by reference.

While the present invention has been described with respect to the particular embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. 

1. An internal voltage generator for use in a semiconductor memory device, comprising: a normal level detecting means for detecting level of an internal voltage relative to a reference voltage; a normal driver for supplying the internal voltage under the control of the normal level detecting means; active period detecting means for detecting an active period to output an active period signal; active level detecting means for detecting the level of the internal voltage relative to the reference voltage in response to the active period signal; a first active driver for supplying the internal voltage under the control of the active level detecting means; active driving controlling means for activating a first active driving signal for a predetermined initial time of the active period in response to the active period signal and the output signal of the first active level detecting means and for activating the first active driving signal depending on the internal voltage relative to the reference voltage after the predetermined initial time of the active period; and a second active driver for supplying the internal voltage in response to the first active driving signal.
 2. The internal voltage generator as recited in claim 1, wherein the active driving controlling means includes: driving time controlling means for generating a time driving signal that is activated for a predetermined time after activation of the active period signal; and additional controlling means for activating the first active driving signal during activation of the time driving signal and for outputting the output signal of the active level detecting means as the first active driving signal during deactivation of the time driving signal.
 3. The internal voltage generator as recited in claim 2, wherein the additional controlling means includes: a buffer for buffering the output signal from the active level detecting means; a NAND gate receiving the output signal from the buffer and the time driving signal; and a first inverter for inverting the output signal of the NAND gate to output the first active driving signal.
 4. The internal voltage generator as recited in claim 3, wherein the buffer has two inverters serially coupled to each other.
 5. An internal voltage generator for use in a semiconductor memory device, comprising: a normal level detecting means for detecting level of the internal voltage relative to a first reference voltage; a normal driver for supplying the internal voltage under the control of the normal level detecting means; active period detecting means for detecting an active period to output an active period signal; first active level detecting means for detecting the level of the internal voltage relative to the first reference voltage in response to the active period signal; a first active driver for supplying the internal voltage under the control of the first active level detecting means; second active level detecting means for detecting the level of the internal voltage relative to the second reference voltage in response to the active period signal; active driving controlling means for activating a first active driving signal for a predetermined initial time of the active period in response to the active period signal and the output signal of the second active level detecting means and for activating the first active driving signal depending on the internal voltage relative to the reference voltage after the predetermined initial time of the active period; and a second active driver for supplying the internal voltage in response to the first active driving signal.
 6. The internal voltage generator as recited in claim 5, wherein the level of the second reference voltage is equal to or higher than the level of the first reference voltage.
 7. The internal voltage generator as recited in claim 6, wherein the active driving controlling means includes: driving time controlling means for generating a time driving signal that is activated for the predetermined time after activation of the active period signal; and additional controlling means for activating the first active driving signal during activation of the time driving signal and for outputting the output signal of the second active level detecting means as the first active driving signal during deactivation of the time driving signal.
 8. The internal voltage generator as recited in claim 7, wherein the additional controlling means includes: a buffer, having a first and a second inverters serially coupled to each other, for buffering the output signal from the second active level detecting means; a NAND gate receiving the output signal from the buffer and the time driving signal; and a third inverter for inverting the output signal of the NAND gate to output the first active driving signal.
 9. An internal voltage generator comprising: a normal driver for supplying an internal voltage; a first and a second drivers for supplying the internal voltage; normal level detecting means for detecting the internal voltage relative to a reference voltage to control driving of the normal driver; active period detecting means for detecting an active period to output an active period signal; active level detecting means for detecting the level of the internal voltage relative to the reference voltage in response to the active period signal to control driving of the first active driver; test mode signal generating means for generating a test mode signal; and active driving controlling means for driving the second active driver without regard to the level of the internal voltage during a predetermined time after activation of the active period signal and for driving the second active driver in response to the test mode signal and the output signal of the active level detecting means after the predetermined time of the active period.
 10. The internal voltage generator as recited in claim 9, wherein the active driving controlling means includes: driving time controlling means for generating a time driving signal that is activated for the predetermined time after activation of the active period signal; and additional controlling means for activating the first active driving signal to control driving of the second active driver during activation of the time driving signal and for outputting the output signal of the active level detecting means as the first active driving signal during deactivation of the time driving signal.
 11. The internal voltage generator as recited in claim 10, wherein the additional controlling means deactivates the first active driving signal if the time driving signal is deactivated and the test mode signal is activated, and outputs the output signal of the active level detecting means as the first active driving signal if the time driving signal is deactivated and the test mode signal is deactivated.
 12. The internal voltage generator as recited in claim 11, wherein the additional controlling means includes: a buffer, having a first and a second inverters serially coupled to each other, for buffering the output signal from the active level detecting means; a NOR gate receiving the output signal of the buffer and the test mode signal; a third inverter for inverting the output signal of the NOR gate; a NAND gate receiving the output signal of the third inverter and the time driving signal; and a fourth inverter for inverting the output signal of the NAND gate to output the first active driving signal.
 13. An internal voltage generator comprising: a normal driver for supplying an internal voltage; a first and a second active drivers for supplying the internal voltage; normal level detecting means for detecting the internal voltage reletive to a first reference voltage to control driving of the normal driver; active period detecting means for detecting an active period to output an active period signal; first active level detecting means for detecting the level of the internal voltage relative to the first reference voltage in response to the active period signal to control driving of the first active driver; second active level detecting means for detecting the level of the internal voltage relative to the second reference voltage in response to the active period signal; test mode signal generating means for generating a test mode signal; and active driving controlling means for driving the second active driver without regard to the level of the internal voltage during a predetermined time after activation of the active period signal and for driving the second active driver in response to the test mode signal and the output signal of the second active level detecting means after the predetermined time of the active period.
 14. The internal voltage generator as recited in claim 13, wherein the level of the second reference voltage is equal to or higher than the level of the first reference voltage.
 15. The internal voltage generator as recited in claim 13, wherein the active driving controlling means includes: driving time controlling means for generating a time driving signal that is activated for the predetermined time after activation of the active period signal; and additional controlling means for activating the first active driving signal to control driving of the second active driver during activation of the time driving signal and for outputting the output signal of the active level detecting means as the first active driving signal in response to the test mode signal during deactivation of the time driving signal.
 16. The internal voltage generator as recited in claim 15, wherein the additional controlling means deactivates the first active driving signal if the time driving signal is deactivated and the test mode signal is activated, and outputs the output signal of the second active level detecting means as the first active driving signal if the time driving signal is deactivated and the test mode signal is deactivated.
 17. The internal voltage generator as recited in claim 16, wherein the additional controlling means includes: a buffer, having a first and a second inverters serially coupled to each other, for buffering the output signal from the second active level detecting means; a NOR gate receiving the output signal of the buffer and the test mode signal; a third inverter for inverting the output signal of the NOR gate; a NAND gate receiving the output signal of the third inverter and the time driving signal; and a fourth inverter for inverting the output signal of the NAND gate to output the first active driving signal.
 18. An internal voltage generator for use in a semiconductor memory device, comprising: an active level detecting means for detecting a level of an internal voltage by comparing the level of the internal voltage and a level of a reference voltage to thereby output a first active driving signal; a first active driver for providing the internal voltage in response to the first active driving signal; a driving time controlling means for generating a time driving signal activated for a predetermined time; an active driving controller for activating a second active driving signal while the time driving signal is activated and for outputting the first active driving signal as the second active driving signal while the time driving signal is inactivated; and a second active driver for providing the internal voltage in response to the second active driving signal.
 19. The internal voltage generator as recited in claim 18, wherein the active driving controller includes: a buffer for buffering the first active driving signal; a NAND gate receiving an output from the buffer and the time driving signal; and a first inverter for inverting an output from the NAND gate to thereby output the second active driving signal.
 20. The internal voltage generator as recited in claim 19, wherein the buffer is provided with a second and a third inverters serially connected each other.
 21. An internal voltage generator for use in a semiconductor memory device, comprising: an active level detecting means for detecting a level of an internal voltage by comparing the level of the internal voltage and a level of a reference voltage to thereby output a first active driving signal; a first active driver for providing the internal voltage in response to the first active driving signal; a test mode signal generating means for generating a test mode signal; a driving time controlling means for generating a time driving signal activated for a predetermined time; an active driving controller for activating a second active driving signal while the time driving signal is activated and for outputting the first active driving signal as the second active driving signal while the time driving signal is inactivated; and a second active driver for providing the internal voltage in response to the second active driving signal.
 22. The internal voltage generator as recited in claim 21, wherein the active driving controller inactivates the second active driving signal while the time driving signal is inactivated and the test mode signal is activated and outputs the first active driving signal while the time driving and the test mode signals are inactivated.
 23. The internal voltage generator as recited in claim 22, wherein the active driving controller includes: a buffer, having a first and second inverters serially connected each other, for buffering the first active driving signal; a NOR gate receiving an output from the buffer and the test mode signal; a third inverter for inverting an output from the NOR gate; a NAND gate receiving an output from the third inverter and the time driving signal; and a fourth inverter for inverting an output from the NAND gate to thereby output the second active driving signal.
 24. An internal voltage generator for use in a semiconductor memory device, comprising: a first active level detecting means for detecting a level of the internal voltage by comparing the level of the internal voltage and a level of a first reference voltage to thereby output a first active driving signal; a first active driver for providing the internal voltage in response to the first active driving signal; a second active level detecting means for detecting the level of the internal voltage by comparing the level of the internal voltage and a level of a second reference voltage; a test mode signal generating means for generating a test mode signal; a driving time controlling means for generating a time driving signal activated for a predetermined time; a active driving controller for activating a second active driving signal while the time driving signal is activated and for outputting an output from the second active level detecting means in response to the test mode signal while the time driving signal is inactivated; and a second active driver for providing the internal voltage in response to the second active driving signal.
 25. The internal voltage generator as recited in claim 24, wherein the level of the second reference voltage is higher than the level of the first reference voltage.
 26. The internal voltage generator as recited in claim 25, wherein the active driving controller inactivates when the time driving signal is inactivated and the test mode signal is activated and outputting the output from the second active level detecting means when the time driving signal and the test mode signal are inactivated.
 27. The internal voltage generator as recited in claim 26, wherein the active driving controller includes: a buffer, having first and second buffers serially connected each other, for buffering the output from the second active level detecting means; a NOR gate receiving an output from the buffer and the test mode signal; a third inverter for inverting an output from the NOR gate; a NAND gate receiving an output from the third inverter and the time driving signal; and a fourth inverter for inverting an output from the NAND gate to thereby output the second active driving signal. 